Method for cleaning textile absorbers

ABSTRACT

A method and system for cleaning textile absorbers that can be recycled. The system includes the use of a particular cleaning fluid, n-propyl bromide, to clean the textile absorbers for reuse. The system may also include a removal component in which excess extraneous substances are removed from the textile absorbers prior to cleaning the textile absorbers.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTINGCOMPACT DISK APPENDIX

Not Applicable.

BACKGROUND OF THE INVENTION

The present invention relates to a method and apparatus for cleaningfabrics.

The desorption or removal of extraneous substances from fabrics is aprevalent industrial process. As used herein, the term “extraneoussubstance” refers to any substance that becomes attached to or isabsorbed by a fabric during the use of the fabric. Extraneous substancescan include dirt, industrial lubricants such as oils, grease, coolants,water, glycol, and solvents, as well as particulates. As a result, thecurrent art contains a variety of different methods by which thesesubstances are either removed from a fabric so that the fabric can bereused.

The steps that are used to separate extraneous substances from fabricsso that the fabrics can be cleaned or recycled for reuse must be chosenso that the desired results: maximum recycling and minimum wastegeneration are achieved. Optimization of recycling inevitably results ina process that is specific to a particular waste stream; that is, thesteps of that process will be dictated by the fabric and the compositionof absorbed extraneous substance.

The optimization of the cleaning process, on the other hand, is dictatedby those steps that will result in the cleanest materials. Further, thegoal of maximum recycle of fabrics and cleanest fabrics is oftenassociated with the generation of harmful wastes to the environment.

In response to the need for a cleaning process that is simple,effective, and allows the recycling of fabrics for reuse, the presentinventor developed a process described in U.S. Pat. Nos. 6,230,353 and6,536,061. Although this process met existing needs, it did not addressthe growing concern regarding typical dry cleaning fluids, such asperchloroethylene. Because various local, state, and federal agenciesconsider these dry cleaning fluids to be hazardous wastes, the use ofthem in a cleaning step necessitates their treatment and/or disposal.Not only is hazardous waste disposal costly, but it imposes significantrequirements for careful handling in order to protect the environment.Perchloroethylene is also considered to be a health hazard to those thatmay become over exposed to its fumes if not properly handled andventilated.

Furthermore, common dry cleaning fluids oftentimes require the use ofsingle to multiple industrial distillers to accommodate their highdistillation points. These types of distillers consume significantenergy resources and require careful monitoring.

Although cleaning methods thought to be environmentally friendlyalternatives to dry cleaning exist, these methods bring with themadditional complications and disadvantages. For example, the use of wetcleaning implicates the environmental regulation of water. Anothercleaning method uses liquid carbon dioxide as an alternative toperchloroethylene. However, this method requires the use of speciallydesigned machines capable of handing the high pressure required tosustain liquid carbon dioxide.

Therefore, there remains a need for a process for removing extraneoussubstances from fabrics that is simple, safe, effective, environmentallysound, and energy conserving.

SUMMARY OF THE INVENTION

The following presents a simplified summary of the invention in order toprovide a basic understanding of some aspects of the invention. Thissummary is not an extensive overview of the invention. It is notintended to identify key or critical elements of the invention or todelineate the scope of the invention. Its sole purpose is to presentsome concepts of the invention in a simplified form as a prelude to themore detailed description that is presented later.

According to its major aspects and briefly stated, the present inventionis a method and system for removing extraneous substances from fabricsso that the fabrics can be recycled for reuse. In the case of thefabrics, recycle means that the fabrics are ready for reuse followingapplication of the present process. Because some of the extraneoussubstances removed, such as oil, are also capable of being recovered andrecycled, in the case of these substances, recycle may require furthersteps.

The present invention has industrial applicability, because it enablesthe cleaning of various materials used for industrial processes so thatthese materials can be reused. For example, such materials as shopcloths and oil-absorbers can be effectively cleaned for reuse withoutthe need to employ environmentally harmful cleaning agents. Althoughthis invention has industrial applicability, it is in no way limited tothis applicability. For example, the present invention may also beapplied to the cleaning of clothes.

The main component of the system is a cleaning component. Fabricsbearing extraneous substances are cleaned through the use of aparticular cleaning fluid. The specific cleaning steps are not criticalto the process as long as the cleaning fluid used is n-propyl bromide.Additionally, the system can include an excess extraneous substanceremoval component that precedes the cleaning component so that lessenergy is spent cleaning the fabrics in the cleaning component.

If the system includes the optional excess substance removal component,excess extraneous substances, such as oil and metal chips, can beremoved from the fabrics by gravity draining by mechanical squeezing, bycentrifuging, or by the combination of these. For example, theseextraneous substances can be drained by placing oil-absorbing materialsinto drums and allowing the substances to drain from the fabrics to thebottoms of the drums. Alternatively, the extraneous substances can bedrained by gravity into a sump. Additionally, extraneous substances canbe removed by manually wringing or squeezing the fabrics. The removedextraneous substances can then be pumped to a settling tank where theycan be removed or recovered by various recovery techniques known in theart.

In the cleaning component of the present system, the fabrics are cleanedby a cleaning technique, which employs the cleaning fluid n-propylbromide. Although the cleaning technique is not critical, a preferredtechnique is dry cleaning. For example, the fabrics can be dry cleanedusing an industrial dry cleaning machine. Additionally, the dry cleaningmachine can be a closed loop machine that is connected to a distiller, adry cleaning fluid tank for storing the dry cleaning fluid, and a wastecontainer. Through the use of a closed loop dry cleaning machine, thecleaning fluid may be distilled and reused for multiple cycles. However,it is also contemplated by the present invention that various cleaningapparatuses and methods can be used other than dry cleaning. If a closedloop dry cleaning machine is used, the effluent from dry cleaning thefabrics is distilled to remove as much extraneous substance from thecleaning fluid as possible and to assure that the dry cleaning fluid,when reused to dry clean the fabrics, is as clean as possible. Althoughthe use of one distiller is sufficient for the process of the presentinvention, it is also contemplated that two distillers be used so thatthe cleaning fluid is distilled twice not only to ensure that thecleaning fluid is as clean as possible when it is reused, but to ensurethere is always sufficient cleaning fluid available for reuse in newcleaning batches. The extraneous substance collected in the distiller isthereafter removed and handled appropriately depending on the type ofextraneous substance.

A feature of the present invention is the use of a particular cleaningfluid that is an environmentally sound improvement over common cleaningproducts, such as chlorinated solvents. The use of n-propyl bromide isan advantageous alternative for chlorinated solvents, such asperchloroethylene. This compound is extremely effective at separatingoils and greases from oil-absorbing materials, such as polypropylene.Furthermore, n-propyl bromide leaves these materials with a fresherscent and a softer feel than the chlorinated solvents. Whereasperchloroethylene may be most effective at removing the types of oilsfound on the human body, n-propyl bromide appears to be more effectiveat removing the types of oils found in industrial processes. Moreimportantly, n-proply bromide is not considered by federal and stateagencies to be a hazardous substance. Accordingly, users of thiscompound do not require all of the permits typically mandated by local,state, and federal agencies. This result greatly reduces compliancecosts. Although n-propyl bromide is on the whole more costly thanchlorinated solvents, these additional costs are more than recouped bythe decrease in energy costs required to incorporate n-propyl bromideinto the cleaning component of the present process. For example, fortypercent less energy is used when n-propyl bromide is the cleaning fluidas when perchloroethylene is used. Moreover, the properties of n-propylbromide are such that a shorter drying time is required for fabrics.Accordingly, throughput of the fabrics is dramatically increased.

Another feature of the present invention is the optional componentincluding the removal of excess extraneous substance. A considerableamount of extraneous substances can be removed from fabrics simply byallowing them to drain. Not only does excess extraneous substance drainreadily from the fabrics, but also particles and metal chips can beremoved in this way. By minimizing the amount of residual lubricants andparticles in the fabrics in this optional component of the presentprocess, more extraneous substance is recovered and the cleaningcomponent is more effective in cleaning the fabrics for recycle.

Other features and advantages of the present invention will be apparentto those skilled in the art from a careful reading of the DetailedDescription of the Invention presented below and accompanied by thedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings,

FIG. 1 is a schematic diagram of the first component of a cleaningsystem according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of the second component of a cleaningsystem according to an embodiment of the present invention; and

FIG. 3 is a flow chart of a process according to an embodiment of thepresent method.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIGS. 1-3 there are illustrated schematic diagrams anda flow chart of a method and apparatus for separating extraneoussubstances from fabrics according to the present invention. It iscontemplated by the present invention that any type of fabric, be itwoven, non-woven, natural, or synthetic, can be cleaned using thefollowing method. Furthermore, it is also contemplated that any type ofextraneous substance that typically attaches to or becomes absorbed byfabrics can be removed or desorbed by the following method. Althoughthere is no end of extraneous substances and fabrics for which thepresent invention is applicable, by way of example, the followingdescription will focus on industrial-type fabrics and extraneoussubstances affecting these fabrics.

The desorption of extraneous substances, such as oil and otherindustrial lubricants, from absorbent materials is a prevalentindustrial process. Absorbent fabrics used in industrial settingsinclude synthetic and natural, woven and non-woven fabrics, which maycome in the form of pads, sheets, shop cloths, and tubular “socks,” andwhich are customarily used in machine shops and metal fabricating plantsto absorb spilled or leaking lubricants. Additionally, the industrialuniforms used in these plants become soiled with similar extraneoussubstances. For convenience, these fabrics will be referred to hereinand the claims that follow as textile absorbers. As used herein,“textile absorbers” refer to fabrics and other manufactured productsmade from natural or manufactured fibers and filaments, as well asyarns, which have the ability to take up another material. Commontextile absorbers include of polypropylene and polyester and cotton.

A goal of the present invention is recycling; in particular, the presentsystem cleans textile absorbers for reuse. The more effective thepresent system is, the more extraneous substance it recovers, thecleaner the textile absorbers are, and the less hazardous waste itgenerates. As discussed, the main component of the present invention isthe cleaning component. However, an optional component to the presentprocess is a removal component in which excess extraneous substance isremoved from the textile fabrics. This optional component is directed tothe separation of and recovery of extraneous substances from the textileabsorbers. In the cleaning component, the textile absorbers are cleanedusing means and method for cleaning the textile absorbers so that theseabsorbers can be reused and so that the production of waste productsduring cleaning is minimized. Waste products are reduced in thiscomponent by using a particular kind of dry cleaning fluid.

Although the removal of excess extraneous substance is an optionalcomponent of the present invention, the cleaning process or componentmay be more effective if excess extraneous substance is removed prior tocleaning. Accordingly, and referring now to FIG. 1, textile absorbers 10are sometimes collected in barrels 12 for a period of time prior tobeginning the present process. While standing in barrels 12, extraneoussubstances, such as oil, lubricants, and solvents will drain downthrough a stack of textile absorbers 10, pooling in the bottom ofbarrels 12. Textile absorbers 10 at the top of the stack will berelatively free of excess extraneous substance; those at the bottom willcontain excess extraneous substance, perhaps being soaked in it. Thelonger the barrels 12 stand undisturbed, the more extraneous substancewill drain to the bottom.

Textile absorbers 10 that are located near the top of the barrels 12 cango directly into the cleaning component of the present process. Textileabsorbers 10 located near the bottom of the barrels 12 can be placed onan elevated coarse grid 20 over a collection basin 22 to drainadditional extraneous substance from them. The longer the textileabsorbers 10 are allowed to drain, the less extraneous substance willhave to be removed from the textile absorbers 10 in the cleaningcomponent of the present invention. Alternatively, textile absorbers 10located near the bottom of the barrels 12 can be manually wrung orsqueezed mechanically so as to remove excess extraneous substance beforethe textile absorbers 10 enter the cleaning component of the presentprocess.

Although the use of the elevated grid 20 and collection basin 22 is anoptional feature of the present invention, if used, preferably a finemesh grid 24 is located below the elevated coarse grid 20. Extraneoussubstance drains through the coarse and fine mesh grids 20, 24, to thelower portion of the basin 22. Particles, dirt, metal chips, andcuttings collect on fine mesh grid 24 and can be removed in a variety ofways, such as vacuuming. If the textile absorbers 10 have been stored inbarrels 12, extraneous substance pooled in the bottom of the barrels 12can be poured directly into collection basin 22.

In order to further remove excess extraneous substances from the textileabsorbers 10 before entering the cleaning component of the presentinvention, the textile absorbers 10 can be centrifuged at a high speedin a centrifuge 30 with a vertical axis 32 of rotation. Preferably, thecentrifuge 30 operates at 900-1200 revolutions per minute (RPM) so thatin approximately three minutes, the excess extraneous substances areremoved so that the textile absorbers 10 have less than 2% andpreferably less than 0.5% extraneous substances remaining.

From collection basin 22 and from centrifuge 30, the extraneoussubstances, such as oil, can then be directly shipped to a processingfacility, such as a refinery. Alternatively, the extraneous substancescan first be transferred to an recovery system. For example, if theextraneous substance is made up mostly of oil, the oil can be pumpedthrough filters 40, 42, using pumps 44, 46, respectively, to a settlingtank 50. Filters 40, 42, remove additional particulate although somewill collect on the fine mesh grid 24 of collection basin 22 and morewill settle to the bottom of the basin 22.

In the settling tank 50, the extraneous substances are allowed to standso that fine particulate settles to the bottom as sludge while the fluidsubstances rise to the top. Water that has mixed with the extraneoussubstances tends to separate below these substances but above theheavier sludge. Settling tank 50 is equipped with a pipe 52, locatedwithin the upper region of the tank 50 and in fluid communication withits interior. When the oil reaches a certain level, it enters pipe 52and flows, by gravity, to a first barrel 54. Periodically, theextraneous substances collected are pumped using pump 56 through a bagfilter 58 to storage tank 60. Preferably, filter 58 is sized to capturesolids having a particle size greater than or equal to approximately 200microns.

Extraneous substances from lower elevations of settling tank 50 drain toan evaporator 64. Heat from a heat source 66 is applied to evaporator 64to remove water from these extraneous substances. Then the extraneoussubstances are skimmed from evaporator 64 and drained to a second barrel68. Periodically, extraneous substances that are collected are pumped bypump 56 to holding tank 60 via bag filter 58.

The extraneous substances recovered from the textile absorbers 10 andseparated from both particulate by bag filter 58 and from water byevaporator 64 can thereafter be shipped to a refinery for furtherprocessing.

In the cleaning component of the present process, textile absorbers 10,following the removal of excess oil by gravity draining, by gravitydraining in combination with centrifuging, by wringing, or squeezing,are cleaned using n-propyl bromide as the cleaning fluid. A commerciallyavailable form of n-propyl bromide exists under the name TECHTRIDE®,which is sold for use in vapor degreasing. However, this form ofn-propyl bromide contains various stabilizers, including ether andbutylene oxide, which although advantageous in degreasing processes, arenot necessary for the present process. Preferably, the cleaning fluid is100% n-propyl bromide or consists essentially of n-propyl bromide.However, the cleaning fluid may also contain the stabilizers in the casethat the particular cleaning method and apparatus dictates it.

Various cleaning methods and apparatuses can be employed in thiscleaning component, and no particular cleaning technique is critical tothe present invention. However, by way of example, a preferred cleaningtechnique is dry cleaning. In the case that dry cleaning is employed,textile absorbers 10 can be cleaned in an industrial dry cleaningmachine 80, shown in FIG. 2, that has been modified for the presentpurposes. The second component can be controlled by a computercontroller 82, operating various valves and pumps and other componentsas will be described, so that the operation can take place efficiently.

The cleaning component, which is illustrated in FIG. 2, also includes adistiller 90 to separate oils from the cleaning fluid. When dry cleaningthe textile absorbers 10 using n-propyl bromide, the distiller 90 mustbe able to achieve a temperature between approximately 70° F. and 150°F. to affect the phase separation. The distillation point of n-propylbromide varies depending on the amount the particular extraneoussubstance with which it is combined. It is understood that thetemperature at which separation occurs will vary as a function of boththe dry cleaning fluid used and the type of lubricant removed, andtherefore an artisan with ordinary skill would alter the temperature ofthe distiller accordingly.

As discussed, the use of n-propyl bromide is a particular feature of thepresent invention. This cleaning fluid is an environmentally sound andadvantageous alternative to commonly used chlorinated solvents, such asperchloroethylene. N-propyl bromide is extremely effective at separatingoils and greases from oil-absorbing materials, such as polypropylene.Furthermore, n-propyl bromide leaves these materials with a fresherscent and softer feel than the chlorinated solvents. Whereasperchloroethylene may be most effective at removing the types of oilsfound on the human body, n-propyl bromide appears to be more effectiveat removing the types of oils found in industrial processes. Moreimportantly, n-proply bromide is not considered by federal and stateagencies to be a hazardous substance. Accordingly, users of thiscompound do not need permits from federal and state agencies. Thisresult greatly reduces compliance costs and permitting fees.

Although n-propyl bromide is more costly than a majority, if not all, ofchlorinated solvents, and can cost as much as three times the cost ofchlorinated solvents, these additional costs are more than recouped bythe decrease in energy costs required to incorporated n-propyl bromideinto the cleaning component of the present process. On average, fortypercent less energy is used when n-propyl bromide is the cleaning fluidas when perchloroethylene is used. Moreover, the properties of n-propylbromide are such that a shortened drying time is required for theoil-absorbing materials. For example, the distillation point of n-propylbromide when used in the dry cleaning process is between approximately90° F., whereas the distillation point of perchloroethylene isapproximately 265° F. Accordingly, the time needed to recycle thetextile absorbers 10 is dramatically reduced and throughput of thetextile absorbers 10 increased. Not only does the low distillation pointof n-propyl bromide save on energy costs, but also it obviates the needfor the use of industrial powered distillers. This lower distillationpoint also results in a safer working environment considering theprocess removes the need to operate equipment at extremely hightemperatures or pressures.

Another advantageous difference between n-propyl bromide andperchloroethylene is that n-propyl bromide is much less dense thanperchloroethylene. For example, 50 gallons of perchloroethylene equalsapproximately 700 lbs, whereas approximately 50 gallons of n-propylbromide equals approximately 580 lbs. Accordingly, there is less stresson the dry cleaning machine when the same amount of n-propyl bromide isused as when perchloroethylene is used.

Still another advantageous property of n-propyl bromide is that itevaporates at a lower temperature than perchloroethylene. Consequently,textile absorbers 10 require a shorter drying time, betweenapproximately 15 minutes to 25 minutes, as opposed to 30 minutes to 60minutes with perchloroethylene.

After textile absorbers 10 are put through a single cleaning cycle orwashing in dry cleaning machine 80, the effluent from the washing ispumped to distiller 90 where it is processed to clean the dry cleaningfluid by distilling the dry cleaning fluid from extraneous substances.The distilled n-propyl bromide from distiller 90 is then pumped to aholding tank 100 for use in dry cleaning machine 80. Preferably, thedistilled n-propyl bromide contains less than approximately 15%extraneous substances. Most preferably, the distilled n-propyl bromidecontains less than approximately 5% extraneous substances. Waste fromdistiller 90 is pumped to waste tank 98 for proper disposal.

Holding tank 100 can be modified from that of conventional dry cleaningmachines. The tank of conventional machines has partitions to definecompartments for separating the n-propyl bromide into batches. In thepresent tank 100, the partitions can be removed or modified so that thecompartments communicate with each other and, if needed, the tank 100 isenlarged so that more n-propyl bromide is available for each load ofpads 10.

Other modifications include replacement of pumps 84 with larger capacitypumps and replacement of smaller electrical solenoid valves withpneumatic stainless steel ball valves 86. In addition to these changes,the dry cleaner's internal lint filter is also removed. An example of anindustrial dry cleaner capable of use with the present invention is theUnion U-2000 L Series in the 80 pound capacity size manufactured byUnion Drycleaning Products of East Point, Ga.

Waste such as particles and metal fines from dry cleaning machine 80 arecollected by trap 96 and vacuumed into waste tank 98.

Textile absorbers 10 are then folded and packaged in clean plastic basfor return to the shipper. Extraneous substances from tank 60 areforwarded to a refinery for processing and reuse. Waste from varioussources is sent to treatment facilities for processing and disposal.

It will be apparent to those skilled in the art that many changes andsubstitutions can be made to the preferred embodiment herein describedwith departing from the spirit and scope of the present invention asdefined by the appended claims.

1. A method for recycling a textile absorber used to absorb extraneoussubstances, said method comprising the step of: cleaning said a textilrabsorber in n-propyl bromide to remove extraneous substances from saidtextile absorber.
 2. The method as recited in claim 1, furthercomprising the step of removing a portion of said extraneous substancesfrom said textile absorber prior to cleaning said textile absorber. 3.The method as recited in claim 2, wherein said removing step is done byplacing said textile absorber in a barrel to drain said extraneoussubstances by gravity.
 4. The method as recited in claim 2, wherein saidremoving step is done by placing said textile absorber on a grid todrain said extraneous substances by gravity.
 5. The method as recited inclaim 2, wherein said removing step is done by centrifuging said textileabsorber.
 6. The method as recited in claim 5, wherein said centrifugingtakes place at a rate of atleast 900 RPM.
 7. The method as recited inclaim 5, wherein said centrifuging takes place at a rate between 900 and1200 RPM.
 8. The method as recited in claim 5, wherein said centrifugingis done until less than approximetely 2% extraneous substances remain insaid textile absorber.
 9. The method as recited in claim 5, wherein saidcentrifuging is done until less than approximetely 0.5% extraneoussubstances remoan in said textile absorber.
 10. The method as recited inclaim 1, further comprisingthe step of distilling said n-propyl bromidefor reuse after said cleaning step.
 11. The method as recited in claim10, wherein said distilled n-propyl bromide contains less thanapproximately 15% extraneous substances.
 12. The method as recited inclaim 10, wherein said distilled n-propyl bromide contains less thanapproximately 5% extraneous substances.
 13. A method for recycling atextile absorber used to absorb extraneous substances, said methodcomprising steps of: removing a first portion of extraneous substancesfrom a textile absorber used to absorb said extraneous subatances; drycleaning said textile absorber in reused n-propyl bromide to remove asecond portion of said extraneous substances from said textile absorber;and distilling said n-propyl bromide to remove said second portion fromsaid n-propyl bromide.
 14. The method as recited in claim 13, whereinsaid n-propyl bromide contains less than approximately 15% extraneoussubstances.
 15. The method as recited in claim 13, wherein said n-propylbromide contains less than 5% extraneous substances.
 16. The method asrecited in claim 13, wherein said removing step is done by placing saidtextile absorber in a barrel to drain said first portion of extraneoussubstances by gravity.
 17. The method as recited in claim 13, whereinsaid removing step is done by placing said textile absorber on a grid todrain said first portion of extraneous substances by gravity.
 18. Themethod as recited in claim 13, wherein said removing step is done bycentrifuging said textile absorber.
 19. The method as recited in claim13, wherein said dry cleaning step is done in an industrial dry cleaningmachine having two distillers.
 20. The method as recited in claim 13,wherein said reused n-propyl bromide consists essentially of 100%n-propyl bromide.